The invention is related to emergency breathing supplies which pierce high pressure air cartridges to supply air through demand regulators to masks or mouthpieces. The emergency breathing devices are used notably in underwater situations to provide breathable air while exiting a craft, such as a helicopter, an aircraft or a vessel. The emergency breathing devices may be used when exiting a smoke or fume-filled space. The breathing devices are intended to supply six to eight minutes of breathable air from small, high pressure cartridges.
The devices must be capable of being stored for long periods and carried for long periods in rough environments. Predecessor devices used stacked springs and lever-type actuators. The stacked springs provided problems because of long and rough storage before use, and the lever-type actuators permitted repositioning into a false, apparently ready position after use. Prior devices provided no indication that an air supply was about to be exhausted.
A need exists for a highly dependable emergency breathing device which operates reliably after long periods of storage and rough carrying, and which gives immediate indications of readiness. A need exists for devices which provide reliable indications of an impending exhausting of an emergency air supply.